The present invention relates to beverage brewers in general and, more particularly, to brewers of tea and coffee which brew a single cup on demand, for use in automatic vending machines.
The prior art brewing devices utilized in automatic vending machines for brewing and dispensing single cups of coffee and tea, on demand, either provide a single brewer for brewing either tea or coffee, depending on the customer's choice, or two completely separate brewers, one for tea and one for coffee, each with its own separate operating mechanism. One of the main problems of utilizing a single brewer to brew either tea or coffee as selected by a customer is taste contamination. For example, if the brewer has just been used to brew coffee and the next customer selects tea, the tea may have a coffee taste to it since there will always be a residual amount of brewed coffee in the brewer which will be swept into the cup and mixed with the tea.
A second problem with using a single brewer in an automatic vending machine involves proper adjustment of the brewing control equipment so as to brew acceptable tea or coffee. The size and volume of the coffee grounds for brewing acceptable coffee in an acceptable period of time differs significantly in most cases from the size and volume of tea grounds necessary to brew an acceptable cup of tea in a similar time. It has been known for some time that in order to reduce the brewing time of fresh ground coffee and tea to a short enough time that it is commercially acceptable in an automatic vending machine, at least part of the brewing process needs to be carried out under pressure so that as the beverage is expelled from the brewing chamber it is passed over the bed of granules or tea leaves at such a rate as to maximize the extraction of flavor into the beverage to be dispensed. However, the pressure differs markedly for the brewing of tea and coffee during essentially the same time period in this environment and adjustments have to be made when switching between the brewing of tea and coffee in the same brewer on subsequent vends from such machines in order to have an acceptable tasting commodity. The relative complexity of such equipment makes the machine more expensive and can result in poor control over the necessary formula of grounds, pressure and time and can result in an inferior brew of coffee or tea. In addition, the difference in fineness of the coffee grounds verses that of tea necessitates the use of a finer filter or screen than is needed or can be used to produce tea in an automatic vending machine environment. This requires a compromise in the mesh of the filter and the grind of the tea and coffee which results in poor quality of either brewed product.
The use of two completely separate brewers solves the taste contamination problem mentioned above, however, such a brewer is much more costly to construct since it doubles the amount of brewing equipment and its associated operating mechanisms. This can become prohibitively expensive. In addition, the use of two completely separate brewing systems is bulky and does not lend itself to packaging in a vending machine where space is at a premium.